Back in the mid 80's I was hired to manufacture 8 additional output ACN's for a 500 console. The transformers were no longer available from the factory. I had worked for the chief engineer & knew the owner of the transformer co. that wound all their transformers.

He wound a dozen for me. I have 4 left, they are new, never been used. 600 to 600 ohm impedance & will handle 30 dbm plus. They are wound bifilar; when I received them I measured the frquency response, it is flat from 25hz to 1.5 mghz & down only 3db @ 3mghz.